This study investigates the existence and use of Tense Aspect and Voice (TAV) in Modern standard Arabic (MSA) and Libyan Dialects (LD) and the effect of these language systems, particularly ‘Libyan dialects (LD)’on the acquisition and use of the English (TAV) by Libyan university students. This study is conducted in two stages. The first stage investigates the existence and use of (TAV) in both MSA and LD, and then it compares these grammatical structures in MSA to those of LD in terms of syntactic structures and the pragmatic use of TAV. The second stage investigates the use of the English (TAV) by Libyan learners of English. The findings of these two stages are compared and contrasted to see the extent to which the presence of (TAV) in Libyan dialects affects the use of English (TAV) by Libyan learners of English and, if there is any influence, which of these two language forms (MSA) or (LD) has more effect on the English use of (TAV). The results of the first stage show some similarities and differences between (MSA) and (LD) in the presence and use of (TAV). That is, some tenses exist in both (MSA) and (LD) and are similarly used, while other tenses are either existent in MSA or LD. The results of the second stage show that both language forms (LD) and (MSA) have a degree of influence on the acquisition and use of English (TAV). However, (LD) appears to have more effect. This is very clear in the use of simple past instead of present perfect and in the use of what is so called ‘activisation’ which is deemed an (LD) marked form as this appears in the participants’ responses when using the English (TAV). Besides this, some other grammatical structures such as the use of continuous and perfect tenses are also affected by (LD).